// SPDX-License-Identifier: GPL-2.0+
/*
 * mpc624.c
 * Hardware driver for a Micro/sys inc. MPC-624 PC/104 board
 *
 * COMEDI - Linux Control and Measurement Device Interface
 * Copyright (C) 2000 David A. Schleef <ds@schleef.org>
 */

/*
 * Driver: mpc624
 * Description: Micro/sys MPC-624 PC/104 board
 * Devices: [Micro/sys] MPC-624 (mpc624)
 * Author: Stanislaw Raczynski <sraczynski@op.pl>
 * Updated: Thu, 15 Sep 2005 12:01:18 +0200
 * Status: working
 *
 * The Micro/sys MPC-624 board is based on the LTC2440 24-bit sigma-delta
 * ADC chip.
 *
 * Subdevices supported by the driver:
 * - Analog In:   supported
 * - Digital I/O: not supported
 * - LEDs:        not supported
 * - EEPROM:      not supported
 *
 * Configuration Options:
 *   [0] - I/O base address
 *   [1] - conversion rate
 *         Conversion rate   RMS noise  Effective Number Of Bits
 *         0    3.52kHz         23uV            17
 *         1    1.76kHz         3.5uV           20
 *         2    880Hz           2uV             21.3
 *         3    440Hz           1.4uV           21.8
 *         4    220Hz           1uV             22.4
 *         5    110Hz           750uV           22.9
 *         6    55Hz            510nV           23.4
 *         7    27.5Hz          375nV           24
 *         8    13.75Hz         250nV           24.4
 *         9    6.875Hz         200nV           24.6
 *   [2] - voltage range
 *         0    -1.01V .. +1.01V
 *         1    -10.1V .. +10.1V
 */

#include <linux/module.h>
#include <linux/comedi/comedidev.h>
#include <linux/delay.h>

/* Offsets of different ports */
#define MPC624_MASTER_CONTROL   0 /* not used */
#define MPC624_GNMUXCH          1 /* Gain, Mux, Channel of ADC */
#define MPC624_ADC              2 /* read/write to/from ADC */
#define MPC624_EE               3 /* read/write to/from serial EEPROM via I2C */
#define MPC624_LEDS             4 /* write to LEDs */
#define MPC624_DIO              5 /* read/write to/from digital I/O ports */
#define MPC624_IRQ_MASK         6 /* IRQ masking enable/disable */

/* Register bits' names */
#define MPC624_ADBUSY           BIT(5)
#define MPC624_ADSDO            BIT(4)
#define MPC624_ADFO             BIT(3)
#define MPC624_ADCS             BIT(2)
#define MPC624_ADSCK            BIT(1)
#define MPC624_ADSDI            BIT(0)

/* 32-bit output value bits' names */
#define MPC624_EOC_BIT          BIT(31)
#define MPC624_DMY_BIT          BIT(30)
#define MPC624_SGN_BIT          BIT(29)

/* SDI Speed/Resolution Programming bits */
#define MPC624_OSR(x)           (((x) & 0x1f) << 27)
#define MPC624_SPEED_3_52_KHZ   MPC624_OSR(0x11)
#define MPC624_SPEED_1_76_KHZ   MPC624_OSR(0x12)
#define MPC624_SPEED_880_HZ     MPC624_OSR(0x13)
#define MPC624_SPEED_440_HZ     MPC624_OSR(0x14)
#define MPC624_SPEED_220_HZ     MPC624_OSR(0x15)
#define MPC624_SPEED_110_HZ     MPC624_OSR(0x16)
#define MPC624_SPEED_55_HZ      MPC624_OSR(0x17)
#define MPC624_SPEED_27_5_HZ    MPC624_OSR(0x18)
#define MPC624_SPEED_13_75_HZ   MPC624_OSR(0x19)
#define MPC624_SPEED_6_875_HZ   MPC624_OSR(0x1f)

struct mpc624_private {
        unsigned int ai_speed;
};

/* -------------------------------------------------------------------------- */
static const struct comedi_lrange range_mpc624_bipolar1 = {
        1,
        {
/* BIP_RANGE(1.01)  this is correct, */
         /*  but my MPC-624 actually seems to have a range of 2.02 */
         BIP_RANGE(2.02)
        }
};

static const struct comedi_lrange range_mpc624_bipolar10 = {
        1,
        {
/* BIP_RANGE(10.1)   this is correct, */
         /*  but my MPC-624 actually seems to have a range of 20.2 */
         BIP_RANGE(20.2)
        }
};

static unsigned int mpc624_ai_get_sample(struct comedi_device *dev,
                                         struct comedi_subdevice *s)
{
        struct mpc624_private *devpriv = dev->private;
        unsigned int data_out = devpriv->ai_speed;
        unsigned int data_in = 0;
        unsigned int bit;
        int i;

        /* Start reading data */
        udelay(1);
        for (i = 0; i < 32; i++) {
                /* Set the clock low */
                outb(0, dev->iobase + MPC624_ADC);
                udelay(1);

                /* Set the ADSDI line for the next bit (send to MPC624) */
                bit = (data_out & BIT(31)) ? MPC624_ADSDI : 0;
                outb(bit, dev->iobase + MPC624_ADC);
                udelay(1);

                /* Set the clock high */
                outb(MPC624_ADSCK | bit, dev->iobase + MPC624_ADC);
                udelay(1);

                /* Read ADSDO on high clock (receive from MPC624) */
                data_in <<= 1;
                data_in |= (inb(dev->iobase + MPC624_ADC) & MPC624_ADSDO) >> 4;
                udelay(1);

                data_out <<= 1;
        }

        /*
         * Received 32-bit long value consist of:
         *      31: EOC - (End Of Transmission) bit - should be 0
         *      30: DMY - (Dummy) bit - should be 0
         *      29: SIG - (Sign) bit - 1 if positive, 0 if negative
         *      28: MSB - (Most Significant Bit) - the first bit of the
         *                                         conversion result
         *      ....
         *      05: LSB - (Least Significant Bit)- the last bit of the
         *                                         conversion result
         *      04-00: sub-LSB - sub-LSBs are basically noise, but when
         *                       averaged properly, they can increase
         *                       conversion precision up to 29 bits;
         *                       they can be discarded without loss of
         *                       resolution.
         */
        if (data_in & MPC624_EOC_BIT)
                dev_dbg(dev->class_dev, "EOC bit is set!");
        if (data_in & MPC624_DMY_BIT)
                dev_dbg(dev->class_dev, "DMY bit is set!");

        if (data_in & MPC624_SGN_BIT) {
                /*
                 * Voltage is positive
                 *
                 * comedi operates on unsigned numbers, so mask off EOC
                 * and DMY and don't clear the SGN bit
                 */
                data_in &= 0x3fffffff;
        } else {
                /*
                 * The voltage is negative
                 *
                 * data_in contains a number in 30-bit two's complement
                 * code and we must deal with it
                 */
                data_in |= MPC624_SGN_BIT;
                data_in = ~data_in;
                data_in += 1;
                /* clear EOC and DMY bits */
                data_in &= ~(MPC624_EOC_BIT | MPC624_DMY_BIT);
                data_in = 0x20000000 - data_in;
        }
        return data_in;
}

static int mpc624_ai_eoc(struct comedi_device *dev,
                         struct comedi_subdevice *s,
                         struct comedi_insn *insn,
                         unsigned long context)
{
        unsigned char status;

        status = inb(dev->iobase + MPC624_ADC);
        if ((status & MPC624_ADBUSY) == 0)
                return 0;
        return -EBUSY;
}

static int mpc624_ai_insn_read(struct comedi_device *dev,
                               struct comedi_subdevice *s,
                               struct comedi_insn *insn,
                               unsigned int *data)
{
        int ret;
        int i;

        /*
         *  WARNING:
         *  We always write 0 to GNSWA bit, so the channel range is +-/10.1Vdc
         */
        outb(insn->chanspec, dev->iobase + MPC624_GNMUXCH);

        for (i = 0; i < insn->n; i++) {
                /*  Trigger the conversion */
                outb(MPC624_ADSCK, dev->iobase + MPC624_ADC);
                udelay(1);
                outb(MPC624_ADCS | MPC624_ADSCK, dev->iobase + MPC624_ADC);
                udelay(1);
                outb(0, dev->iobase + MPC624_ADC);
                udelay(1);

                /*  Wait for the conversion to end */
                ret = comedi_timeout(dev, s, insn, mpc624_ai_eoc, 0);
                if (ret)
                        return ret;

                data[i] = mpc624_ai_get_sample(dev, s);
        }

        return insn->n;
}

static int mpc624_attach(struct comedi_device *dev, struct comedi_devconfig *it)
{
        struct mpc624_private *devpriv;
        struct comedi_subdevice *s;
        int ret;

        ret = comedi_request_region(dev, it->options[0], 0x10);
        if (ret)
                return ret;

        devpriv = comedi_alloc_devpriv(dev, sizeof(*devpriv));
        if (!devpriv)
                return -ENOMEM;

        switch (it->options[1]) {
        case 0:
                devpriv->ai_speed = MPC624_SPEED_3_52_KHZ;
                break;
        case 1:
                devpriv->ai_speed = MPC624_SPEED_1_76_KHZ;
                break;
        case 2:
                devpriv->ai_speed = MPC624_SPEED_880_HZ;
                break;
        case 3:
                devpriv->ai_speed = MPC624_SPEED_440_HZ;
                break;
        case 4:
                devpriv->ai_speed = MPC624_SPEED_220_HZ;
                break;
        case 5:
                devpriv->ai_speed = MPC624_SPEED_110_HZ;
                break;
        case 6:
                devpriv->ai_speed = MPC624_SPEED_55_HZ;
                break;
        case 7:
                devpriv->ai_speed = MPC624_SPEED_27_5_HZ;
                break;
        case 8:
                devpriv->ai_speed = MPC624_SPEED_13_75_HZ;
                break;
        case 9:
                devpriv->ai_speed = MPC624_SPEED_6_875_HZ;
                break;
        default:
                devpriv->ai_speed = MPC624_SPEED_3_52_KHZ;
        }

        ret = comedi_alloc_subdevices(dev, 1);
        if (ret)
                return ret;

        /* Analog Input subdevice */
        s = &dev->subdevices[0];
        s->type         = COMEDI_SUBD_AI;
        s->subdev_flags = SDF_READABLE | SDF_DIFF;
        s->n_chan       = 4;
        s->maxdata      = 0x3fffffff;
        s->range_table  = (it->options[1] == 0) ? &range_mpc624_bipolar1
                                                : &range_mpc624_bipolar10;
        s->insn_read    = mpc624_ai_insn_read;

        return 0;
}

static struct comedi_driver mpc624_driver = {
        .driver_name    = "mpc624",
        .module         = THIS_MODULE,
        .attach         = mpc624_attach,
        .detach         = comedi_legacy_detach,
};
module_comedi_driver(mpc624_driver);

MODULE_AUTHOR("Comedi https://www.comedi.org");
MODULE_DESCRIPTION("Comedi driver for Micro/sys MPC-624 PC/104 board");
MODULE_LICENSE("GPL");